The research proposed in this application aims to develop ECI Biotech's promising technology toward improved diagnosis of periprosthetic joint infection (PJI), and reduction in the unwarranted antimicrobial intervention. Criteria for PJI diagnosis have not been standardized in clinical practice, and symptoms of PJI are sometimes difficult to distinguish from other non-infectious causes of inflammation and pain. Discrimination between infection and other causes of pain/inflammation is crucial to choosing effective treatment and to avoid unnecessary use of antibiotics and/or multistage surgery. An initial feasibility study performed by ECI clearly identified two target markers for PJI, when screened against a cohort of clinical synovial fluid samples, gathered from patients with symptoms of PJI. The aim of this application is to transition one or both of these targets from the laboratory-based assay used for initial screening to a prototype point-of- care (PoC) device for future commercialization. In the first aim, the target markers will be integrated into a lateral flow strp PoC diagnostic device. The prototype device will be optimized to mitigate possible cross- reactivity and interference from synovial fluid, especially fluids from persons with autoimmune disorders that involve the synovial fluid especially (rheumatoid arthritis, etc.) In the second aim the prototype device will be tested against a large cohort of patient samples (200+) gathered and banked at the Mayo Clinic, collected from patients undergoing surgical revision for possible PJI. The infection status of these patients will blinded to ECI researchers during assay performance. Diagnosis using ECI's technology is expected to reach 95% accuracy, a significant improvement over current modes of diagnosis currently in use. PUBLIC HEALTH RELEVANCE: Criteria for diagnosis of periprosthetic joint infection (PJI) are not standardized among clinicians, and depend largely on assessment of patient immune response factors, rather than directly assaying for pathogen markers. Misdiagnosis can lead to either inadequate treatment when infections are missed or unnecessary antimicrobial and surgical interventions for infection diagnosis in a joint where no infection actually exists. ECI Biotech's has clearly identified two novel markers for detection of infection, which depend on direct markers of pathogenic microbes. Development of ECI Biotech's laboratory assay for PJI in a point-of-care device for commercialization will improve the rate of correct diagnoses, thereby improving patient care and quality of life.